JPH11338309A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent jitter, etc., caused by torque fluctuation by coaxially providing a granular fluidized body enclosed damper in which granular fluidized body is enclosed with the turning shaft of at least either of an electrostatic latent image holding body and a developer carrier. SOLUTION: A developing roller 3 rotates in a direction reverse to that of a photoreceptor drum 1 in terms of the rotating direction of the roller 3, that is, the roller 3 rotates so that the moving direction of the surface of the roller 3 at a part where the roller 3 is opposed to the drum 1 is the same direction as the moving direction of the surface of the drum 1. The circumferential speed of the roller 3 is 1.5 times as high as that of the drum 1. The granular fluidized body enclosed damper 12 is coaxially fixed to the rotating shaft 11 of the drum 1. The damper 12 is constituted of an outer shell case 13 fixed to the shaft 11 of the drum 1, and an inertial body 14 which is provided inside the case 13 and coaxially with the case 13, and which has a gap with the inside peripheral surface of the case 13. The gap between the peripheral surfaces of the case 13 and the body 14 is filled with silica gel 15 being the granular fluidized body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic latent image holding member, and a developer holding member supported by a developing unit for holding and transporting a developer. The present invention relates to an image forming apparatus for visualizing an electrostatic latent image formed on a developing device using a developer on a developer carrier.

[0002]

2. Description of the Related Art As an electrophotographic developing method of an image forming apparatus generally used in the related art, a carrier of magnetic powder is held on a nonmagnetic developing sleeve having a built-in magnet roller, and a toner as a developer is used. In a two-component developing method in which the toner is transported to a developing step with a photosensitive drum using α-Si, selenium, OPC, or the like.

The one-component developing method using no carrier has a simple structure and can be reduced in size, and has advantages in terms of cost and maintenance. In particular, the non-magnetic one-component method using no magnetic toner is preferable. Since the magnet roller is not used, there is an advantage that the mechanism is simpler and a compact, inexpensive developing device with a clear image can be obtained.

In the two-component developing method, a carrier is raised and an electrostatic latent image formed in advance on the surface of a photoreceptor drum is supplied with toner held on the surface of the carrier and developed. The toner held on the carrier surface is previously charged to a desired charge amount by being stirred by a paddle or mixing in a toner hopper.

In the case of the magnetic one-component developing system, similarly to the two-component developing system, the magnetic toner is conveyed by a non-magnetic developing sleeve having a built-in magnet roller, and a developing sleeve having a predetermined gap and a photosensitive drum are provided. A non-contact development method in which an alternating electric field is applied during the development to cause the toner to fly back and forth for development, or a contact development method in which development is achieved by making the toner ears larger and contacting the electrostatic latent image on the surface of the photosensitive drum There are two methods. The former requires a developing bias in which an alternating current is superimposed on a direct current, and requires a complicated power supply and a high breakdown voltage of the developing device. The result is a poor Hi-γ image.

The non-magnetic one-component developing system includes a non-contact developing system in which an alternating electric field is applied between a developing roller provided with a predetermined gap and a photosensitive drum, and toner is reciprocated to perform development. It can be broadly classified into a contact development method in which the elastic developing roller and the photosensitive drum are brought into contact.The former requires a developing bias in which alternating current is superimposed on direct current, and requires a complicated power supply and a high breakdown voltage of the developing device. On the other hand, the latter requires only a simple DC developing bias power supply.

However, in any of the developing methods, if the frictional resistance of the photosensitive drum or the developing roller fluctuates in the developing step (between the photosensitive drum and the developing roller), the back of the gear or the coupling portion of the coupling is changed. 40 due to rush
Jitter or banding (line perpendicular to the traveling direction of the photosensitive drum, band-like density unevenness, misalignment) of about 100 Hz to 100 Hz occurs. It may appear as streaks or band-like unevenness in black and white. In the two-component developing method, such a phenomenon is likely to occur due to the fluctuation of the frictional resistance (load) between the carrier on the surface of the non-magnetic sleeve and the photosensitive drum, and the elastic developing roller is brought into contact with the photosensitive drum in the one-component developing method. It appears more prominently in the developing system. In particular, in a one-component contact developing system using an elastic developing roller,
Since a peripheral speed difference is provided for the photoconductor drum, when the toner layer on the developing roller is supplied or developed almost entirely to the photoconductor drum, the rubbing resistance becomes extremely large and the image is elongated. In some cases.

As a conventional method, Japanese Patent Laid-Open No. 6-95562 discloses a method in which an inertia member is provided on a shaft and an elastic damper is used to suppress the occurrence of such jitters and banding. It has been disclosed. Also, Japanese Patent Application Laid-Open No. Hei 6-95563 discloses a method of increasing an attenuation ratio by contacting an oil sealing member.
Japanese Patent Publication No. 140841 discloses a method in which a mass member is provided in a photosensitive drum via a damping member, and vibration is attenuated while increasing the moment of inertia.

[0009]

SUMMARY OF THE INVENTION
In a developing device having a photosensitive drum and a magnetic brush on a developing sleeve, or a developing device having a photosensitive roller and a developing roller holding toner on the surface, the vibration of each unit originally blurs a latent image or a visible image on the photosensitive drum. As a result, jitter and banding on the image occur.

On the other hand, since the photosensitive drum receives a force to move in the rotating direction due to the frictional resistance between the developing sleeve or the developing roller and the photosensitive drum, the rotation is always performed by the backlash of the gear and the coupling. Not stable. As a result, jitter and banding are seen in the image. In particular, in a magnetic brush or a one-component contact developing method,
Since the peripheral speed of the developing sleeve (developing roller) is higher than that of the photosensitive drum, the photosensitive drum is further accelerated, which may result in a phenomenon that the image is elongated.

For example, taking the one-component contact developing system as an example, focusing only on the developing roller, both the toner layer forming area and the toner layer non-forming area are formed of the same material and the same outer diameter over the entire area. Was. For this reason, in the contact developing method in which the photosensitive drum and the developing roller are pressed against each other with a relative speed difference, the frictional resistance between the both ends of the developing roller on which the toner is not adhered and the photosensitive drum becomes excessive, and the photosensitive drum and The load torque of the developing roller increases and fluctuates. Furthermore, this causes the rotation of the photoconductor drum and the developing roller to become unstable, so that there is a disadvantage that image unevenness occurs particularly in the sub-scanning direction (transfer sheet transport direction).

Further, even if it is attempted to eliminate the fluctuation in rotation by bringing only the toner layer forming area on the developing roller into contact with the photosensitive drum, the toner is transferred to the photosensitive drum in the developing process. As a result, a difference occurs in the slip level between the developing roller and the photosensitive drum. further,
In addition, when an elastic developing roller is used, the outer diameter tends to change due to environmental changes, especially temperature changes, and the rubbing resistance changes. Fluctuations in load torque cannot be completely eliminated. The two-component developing method also has the same drawbacks as the one-component developing method because the dimensional changes of the components due to the environment occur similarly.

In the non-contact developing system, although the fluctuation of the rubbing resistance is slightly improved, the natural frequency of the component is not constant, and the effect of the vibration preventing member is changed in all environments and changes over time. Component wear).

As a solution to such a problem, as described above, there is a method of stabilizing the rotation by installing an inertia (inertia member) or a dynamic damper on the photosensitive drum. It was necessary to install a large inertia member in order to suppress the noise. Further, in order to stabilize the rubbing resistance, a brake is proposed. However, in any case, a mechanism for absorbing the fluctuation of the rotation speed caused by the fluctuation of the rubbing resistance is complicated and is not effective. It was thin.

The inertia members described in JP-A-6-95562, JP-A-6-95563, and JP-A-7-140841 are mounted inside the photosensitive drum (Japanese Patent Laid-Open No. 6-95563). No. 95562, the dynamic damper is fixed integrally), and the mass and the moment of inertia of the member fixed integrally with the photosensitive drum are considerably large. And a motor having a large starting torque is required. In addition, there is a problem that the stop time of the photosensitive drum becomes longer at the time of stopping.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an object of sealing a viscous fluid in which a viscous fluid is sealed coaxially with a rotation axis of at least one of an electrostatic latent image holder and a developer carrier. By providing a damper, the object is to surely prevent jitter and banding due to torque fluctuation.

[0017]

According to one aspect of the present invention, there is provided an electrostatic latent image holding member, and a developer holding member supported by a developing unit and holding and transporting the developer. An image forming apparatus which visualizes an electrostatic latent image formed on a peripheral surface of the electrostatic latent image holding member with a developer of a developer carrier, wherein the electrostatic latent image holding member or the developer A viscous fluid enclosing damper enclosing the viscous fluid coaxially with at least one of the rotation axes of the carrier is provided.

According to a second aspect of the present invention, there is provided a viscous fluid-filled damper having an outer shell that is coaxial with the rotation axis and rotates together with the rotation axis, and an outer diameter smaller than the inner diameter of the outer cylinder. The rotary inertia body is rotatable coaxially and freely with respect to the outer shell cylinder, and the viscous fluid is sealed between the circumferential surfaces of the outer shell cylinder and the rotary inertia body.

According to a third aspect of the present invention, the outer cylinder is integrally fixed to at least one of the rotating shafts of the electrostatic latent image holder and the developer carrier.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 of an electrophotographic digital copying machine of a one-component contact developing system which is an image forming apparatus of the present invention.
Will be described with reference to FIG.

In the electrophotographic digital copying machine according to the first embodiment, a one-component contact developing unit is disposed so as to face the photosensitive drum 1 as an electrostatic latent image holding member. The contact depth between the developing roller 3 rotatably supported by the casing 2 of the one-component contact developing unit and the photosensitive drum 1 is small in distortion and deformation, and its influence is negligible, and polyacetal excellent in rigidity is provided. The contact depth is regulated by using a contact depth setting roller 5 integrally formed with the rotating shaft 4 of the developing roller 3 with resin, and the contact depth δ is set to 0.1 mm.

The photosensitive drum 1 is rotatably driven by a drive motor 6 via gears 7 and 8, and a developing roller 3
Are rotationally driven by a drive motor 9 via a coupling 10.

The rotation direction of the developing roller 3 is opposite to that of the photosensitive drum 1, that is, the moving direction of the surface of the developing roller 3 at the portion facing the photosensitive drum 1 is the moving direction of the surface of the photosensitive drum 1. The peripheral speed of the developing roller 3 is 1.5 times the peripheral speed (process speed) of the photosensitive drum 1. A viscous fluid-filled damper 12 is coaxially fixed to the rotating shaft 11 of the photosensitive drum 1.

As shown in FIGS. 2 and 3, the viscous fluid-filled damper 12 includes an outer shell case 13 fixed to the rotating shaft 11 of the photosensitive drum 1, and an outer shell case 13 inside the outer shell case 13. An inertia body 14 installed coaxially with the inner case 13 and having a gap with the inner circumferential surface of the outer case 13, and a silica gel as a viscous fluid filled between the outer case 13 and the outer circumferential surface of the inertia body 14. 15.

Inertia 14 in viscous fluid-filled damper 12
Is installed so that it can rotate freely inside the outer shell case 13. A gap is formed between the inner circumferential surface of the outer shell case 13 and the outer circumferential surface of the inertial body 14, and the gap is filled with the silica gel 15, so that the silica gel 15 can be freely formed inside the outer shell case 13. Rotating inertial body 1
4 is formed so as to wrap around the outer shell case 13 due to the viscous resistance of the silica gel 15. That is, when the outer shell case 13 is rotating at a constant speed, the inertial body 14 is also rotating at a constant speed at the same speed.

Further, even when an instantaneous acceleration / deceleration occurs in the outer shell case 13, the inertia body 14 tries to keep rotating at a constant speed due to its own inertia. At this time, the inertia body 14 wraps around the outer shell case 13 due to the viscous resistance of the silica gel 15,
It works to keep the outer shell case 13 rotating at a constant speed. That is, the rotational speed of the viscous fluid-filled damper 12 as a whole does not change instantaneously.

Accordingly, the viscous fluid-filled damper 12 rotates following the rotation of the photosensitive drum 1, and the inertia body 14 contained therein is rotated by the drag of the outer shell case 13 due to the viscosity of the silica gel 15. Has inertia.
That is, the photosensitive drum 1 and the viscous fluid-filled damper 12
Is rotating at a constant speed, the outer shell case 13 and the inertial body 14 are rotating at a constant speed.

On the other hand, the contact depth δ fluctuates due to the influence of the runout of the developing roller 3 and the runout of the contact depth setting roller 5 and the shape accuracy of the photosensitive drum 1. The rubbing resistance fluctuates. As a result, a fluctuation torque is applied in the rotation direction of the photoconductor drum 1 and the rotation speed of the photoconductor drum 1 tends to fluctuate. However, the inertia of the inertia body 14 itself and the silica gel By virtue of the viscous resistance of the photosensitive drum 1, the fluctuation torque of the photosensitive drum 1 can be reduced and the rotational speed can be maintained.

For example, as an electrophotographic digital copying machine, an electrophotographic digital copying machine AR5130 manufactured by Sharp Corporation.
Alternatively, as a result of an experiment using an AR5130 modified experimental machine, a moment of inertia 95
When a flywheel made of a SECC steel sheet of kg · cm ² is installed, if the frictional resistance between the photosensitive drum 1 and the developing roller 3 fluctuates, it may appear as a density difference on an image due to jitter. When the viscous fluid-filled damper 12 having the same moment of inertia is provided, jitter and banding do not appear even if the frictional resistance changes. Therefore, when the silica gel 15 inclusion type is used, the effect is large even if the magnitude of the moment of inertia is the same, and it is possible to eliminate all chattering of the cleaning blade and load fluctuation of the charging / transfer roller. .

This effect does not depend on the process speed, and similar results were obtained from 25 mm / s to 320 mm / s. Further, this effect is not obtained only in a specific developing method, but is particularly effective in a one-component contact developing method using an elastic developing roller that maximizes the frictional resistance between the photosensitive drum and the developing roller.

A second embodiment of the electrophotographic digital copying machine of the one-component contact developing system of the present invention will be described with reference to FIGS.

The basic structure of the electrophotographic digital copying machine of the second embodiment is almost the same as that of the first embodiment.
S is attached to the end of the photosensitive drum 1 where the gear 8 of the rotating shaft 11 is provided.
An ECC steel flywheel 16 is provided coaxially.
A viscous fluid-filled damper 12 is coaxially provided at one end of the rotation shaft 4 of the developing roller 3.

A toner supply roller 17 is brought into pressure contact with the developing roller 3. The rotation direction of the toner supply roller 17 is the same as that of the developing roller 3, that is, the two rollers at the portion facing the developing roller 3. The directions of movement of the surfaces are opposite to each other.

The toner supplied to the developing roller 3 by the bias voltage while being frictionally charged by the toner supply roller 17 is conveyed to a position where the toner layer regulating member 18 comes into contact with the rotation of the developing roller 3. The toner layer regulating member 18 made of a plate-shaped metal material has a front end or an abdomen near the front end pressed against the developing roller 3.
The toner on the developing roller 3 is regulated to a predetermined charge amount and thickness, and is conveyed to a development area, which is a portion facing the photosensitive drum 1, and enters a development process.

Developing roller 3 not used in developing step
The undeveloped toner on the upper side returns to the inside of the developing device by the rotation of the developing roller 3.
The charged charges are removed by the undeveloped toner charge removing means 19 on the developing roller 3 provided between the developing roller 7 and the toner tank (hereinafter, referred to as the toner tank) by pressing the toner supply roller 17 at the inlet.
It is separated and collected in a hopper and reused.

The screw 20 conveys the toner tank stored in a hopper (not shown) into the developing device. The screw 20 and the toner supply roller 17 are given a driving force by a gear train (not shown) from the developing roller 3.

The operation of the electrophotographic digital copying machine of the one-component contact developing system having the above construction will be described. The toner stored in the hopper is conveyed by the screw 20 into the developing device. The developing roller 3 includes the toner supply roller 1
7 are in pressure contact, and the rotation direction of the toner supply roller 17 is the same as that of the developing roller 3, that is, the moving directions of the surfaces of both rollers at the portion facing the developing roller 3 are opposite to each other. I have. Toner supply roller 1
Reference numeral 7 uses the same material as the developing roller 3, and the electric resistance can be adjusted with the same resistance adjusting material as the developing roller 3. In order to further increase the elasticity, a foamed material is used, and the amount of the foaming agent is larger than that of the developing roller 3 to manufacture.

A bias voltage is applied to the toner supply roller 17 from a bias power supply 21, and the bias voltage is applied in a direction of electrically pushing the toner toward the developing roller 3.
For example, in the case of a negative polarity toner, a large bias voltage is applied to the negative side. The toner that is frictionally charged by the toner supply roller 17 and supplied to the developing roller 3 by the bias voltage is conveyed to a position where the toner layer regulating member 18 comes into contact with the rotation of the developing roller 3. The tip of the toner layer regulating member 18 or the abdomen near the tip is pressed against the developing roller 3, and the toner on the developing roller 3 is regulated to a predetermined charge amount and a predetermined thickness by a predetermined set pressure and a predetermined position. It is transported to the area and enters the development process.

Developing roller 3 not used in developing step
The undeveloped toner on the upper side returns to the inside of the developing device by the rotation of the developing roller 3.
The charged charges are removed by the charge removing means 19 of the undeveloped toner on the developing roller 3 provided between the developing rollers 7, and the toner is peeled and collected in the hopper by the pressure contact of the toner supply roller 17 and used.

On the other hand, the surface of the photosensitive drum 1 is charged to a desired potential by a corona charger or a contact roller charging device (not shown), and a latent image potential is formed by a separately provided exposure device.

The photoreceptor drum 1 has an underlayer coated on a metal or conductive substrate, a carrier generation layer (CGL) as an upper layer, and a carrier transfer layer mainly composed of polycarbonate as an outermost layer. Layer (CT
L) is applied to the thin film. The charged potential (charge) of the charged photosensitive drum 1 is canceled by a carrier generated from CGL by exposure of a desired portion, lamp light in an analog machine, and generally laser light in a digital machine, so Leads to formation.

The electrostatic latent image formed on the photosensitive drum 1 rotates and is transported to a region corresponding to the developing roller 3. In the developing area, the developing roller 3 is pressed against the photosensitive drum 1, and the toner whose charge and layer thickness are regulated to a desired value in advance moves to the photosensitive drum 1 according to the latent image pattern and is visualized. .

After the latent image potential of the photosensitive drum 1 is visualized with toner, the photosensitive drum 1 rotates or moves and is conveyed to the transfer area of the transfer device. Then, the recording paper fed separately by the paper feeding device is conveyed to the transfer area and comes into contact with the toner image on the photosensitive drum 1 in synchronization. The transfer device may be a contact roller type in the case of a charger type provided with a high-voltage power supply, and a voltage of a polarity for moving the toner of the photosensitive drum 1 to the recording paper is applied by any means, and the photosensitive drum 1 The upper toner image is moved and transferred to recording paper.

The recording paper is conveyed after the toner image is transferred, and generally the toner image on the recording paper is melted and fixed on the recording paper by a heat fixing device, and is discharged. On the other hand, the untransferred toner remaining on the photosensitive drum 1 after passing through the transfer area is removed from the photosensitive drum 1 by a cleaner, and the potential is refreshed by a light discharging lamp or a contact discharging means for erasing residual charges. Continue with the first step.

More specifically, the conditions of the second embodiment are as follows. The photosensitive drum 1 is a negatively charged photosensitive drum having a diameter Dp = 65 mm and a conductive substrate grounded and charged to a surface potential of -550 V. 5, the peripheral speed Vp = 190 in the direction of arrow X in FIG.
It is rotating at mm / s.

The developing roller 3 is added with a conductive agent such as carbon black, and has a volume resistivity of about 10 ¹⁶ Ωcm.
-A conductive elastic developing roller made of conductive urethane rubber having a hardness of 60 to 70 degrees and having a diameter Dd of 34 mm, rotating at a peripheral speed Vd of 285 mm / s in the direction of arrow Y in FIG.
A developing bias power supply 22 is connected via a shaft of a conductive support (stainless steel, conductive resin, etc.) having a diameter D ₁ = 18 mm.
E ₁ = voltage of -250V is applied, is pressed against through the toner layer to the photosensitive drum 1 so that the contact depth 0.1~0.5mm by.

The toner supply roller 17 of a conductive urethane foam having a volume resistivity of about 10 ⁵ Ωcm and a cell density of about 3 cells / mm and having a diameter Dt = 20 mm, which serves both for stirring the toner and removing the toner after the development, has a contact depth of 0 mm. 5 to 1 mm, and comes into contact with the developing roller 3 and has a peripheral speed Vt = 170 in the direction of arrow Z in FIG.
mm / s, and a bias voltage of E ₂ = −350 V is applied by a supply bias power supply 21 via a shaft of a conductive support (stainless steel, conductive resin, or the like) having a diameter D ₂ = 8 mm. .

The non-magnetic one-component toner, which has been negatively precharged by the toner supply roller 17 and applied to the surface of the developing roller 3, is rotated by the rotation of the developing roller 3 to form a toner layer regulating member 18.
Is transported to a position where it contacts. Toner layer regulating member 18
Is a conductive (stainless steel, phosphor bronze, conductive resin, etc.) plate-like member having a thickness of 0.1 to 0.2 mm, and has a cantilever leaf spring structure having a free end on the upstream side in the rotation direction of the developing roller 3, the developing roller 3 abuts at a linear pressure 15~30gf / cm, E ₃ by the toner layer regulating member bias power supply 23
= −350 V bias voltage is applied.

The toner layer on the developing roller 3 has a toner adhesion amount of about 0.6 to 0.8 mg /
After being regulated to cm ² and the toner charge amount is about −10 to −15 μC / g, the toner is conveyed to a development area in contact with and opposed to the photosensitive drum 1 by rotation of the development roller 3 to perform contact reversal development.

The toner charge removing means 19 includes the developing roller 3
And has a sealing function for preventing toner from leaking from below, and uses a conductive film having a thickness of 0.3 mm ± 0.1 mm and an electric resistance of 10 ³ to 10 ⁶ Ω. A potential difference of about −50 V or more with respect to the developing roller 3 is set by a potential or a bias power supply 24 for toner charge removing means, and the conductive surface thereof is in contact with the developing roller 3.

When the effective width in the axial direction of the one-component toner layer formed on the developing roller 3 is represented by Lf, the effective width of the toner charge removing means 19 after the developing process is represented by Ld, and the residual width on the developing roller 3 is represented by Ld. If Ld ≧ Lf is set so that the toner charge removing means 19 is sufficiently in contact with the end of the toner layer, the charge of the residual toner becomes uniform, thereby preventing defective toner peeling and uneven supply of the toner by the toner supply roller 17. be able to.

The toner charge removing means 19 may be a conductive member such as an aluminum vapor-deposited film. Further, if it is not necessary to remove the toner charge and only to seal the lower part of the developing roller 3, a mylar film or the like may be used. In this case, the bias power supply 24 for the toner charge removing means is not required.

The developing roller 3 uses an elastic member having a relative dielectric constant of about 10 and has a single-layer structure of a conductive rubber layer around a metal or low-resistance resin core (shaft) as described below. It is formed. That is, a resin selected from EPDM, urethane, silicon, nitrile butadiene rubber, chloroprene rubber, styrene butadiene rubber, butadiene, and the like, and one or more of conductive fine particles, carbon, and TiO ₂ as an electric resistance adjusting material. Those based on dispersion-type resistance adjusting resin dispersed and mixed using, ionic conductive material, for example, sodium perchlorate, calcium perchlorate, inorganic ionic conductive material such as sodium chloride, etc., one or more When a foaming agent is used in the foaming / mixing step, a silicon-based surfactant (polydialkylsiloxane, polysiloxane-polyalkylenoxide block copolymer) is used. ) Is appropriate.

The developing roller 3 has an effective roller resistance r of the developing roller 3 and a developing current i flowing through the developing operation.
A voltage drop Ed = ir is generated internally. By appropriately setting the effective roller resistance r, the effective developing bias acting on the surface of the developing roller 3 is reduced, the steep and binary developing characteristics are adjusted to the desired developing characteristics, and the gradation is adjusted. Performance can be improved.

The toner supply roller 17 is made of polyurethane and carbon black (ISAF, HAF, GPF, SRF).
And the like, and the mixture is stirred and foamed with a foaming machine, and then heated and blown to form a sponge around the metal shaft of the metal core. As the polyurethane to be used, a flexible polyurethane foam or a polyurethane elastomer is suitable. After injection and heat molding of both the developing roller 3 and the toner supply roller 17, the outer shape is polished with a grindstone to finish to a desired surface property and outer diameter.

The toner is generally referred to as a high-resistance toner. The toner is obtained by mixing and kneading carbon black into a polyester resin or a styrene-acryl copolymer of a base resin, and blending an appropriate amount of a charge control agent (CCA) or a vulcanization control agent. ,
After the pulverizing step, a mixture of silica and the like as an external additive is used.

In the above configuration, the developing roller 3
And the toner supply roller 17, or the developing roller 3 due to a change in the rubbing resistance between the developing roller 3 and the toner layer regulating member 18.
May occur, and the toner layer formation may become unstable.

Further, even when the rotation is initially stable, when the gears and the coupling wear over time and the backlash increases, image unevenness due to fluctuations in the rotation speed of the developing roller 3 appears. There are cases.

By providing a viscous fluid-filled damper 12 on the drive shaft 4 of the developing roller 3 in order to obtain good peripheral speed stability, fluctuations in the rotational speed and vibration of the developing chamber 3 can be suppressed. Good image quality without image unevenness in the sub-scanning direction (transfer paper transport direction) was obtained.

For example, the inertia body 14 having a moment of inertia of 516 g · cm ² and the silica gel 1 are attached to the rotating shaft 4 of the developing roller 3.
When the viscous fluid-filled damper 12 enclosing 5 is additionally fixed, it is possible to eliminate jitter density unevenness on an image of about 100 Hz to 120 Hz. This effect did not depend on the process speed, and similar results were obtained from 25 mm / s to 320 mm / s. Further, by providing the viscous fluid-filled damper 12 coaxially on the photosensitive drum 1 as shown in the first embodiment, a greater effect on jitter and banding on an image was obtained.

A third embodiment of the electrophotographic digital copying machine of the two-component developing type according to the present invention will be described with reference to FIGS.

In the electrophotographic digital copying machine according to the third embodiment, a two-component developing unit is disposed so as to face the photosensitive drum 31 as an electrostatic latent image holding member. The contact depth between the photosensitive drum 31 and the developing sleeve 33 as a developer carrier rotatably supported on the casing 32 of the two-component developing unit is slightly distorted or deformed, and the effect thereof can be ignored. The contact depth is regulated by using a contact depth setting roller 35 integrally formed with the rotating shaft 34 of the developing sleeve 33 with a rigid polyacetal resin, and the contact depth δ is set to 0.8 mm.

The photosensitive drum 31 is driven to rotate by gears 37 and 38 by a drive motor 36, and the developing sleeve 33 is coupled to a coupling 40 by a drive motor 39.
Is driven to rotate.

The rotation direction of the developing sleeve 33 is opposite to that of the photosensitive drum 31, that is, the moving direction of the surface of the developing sleeve 33 at the portion facing the photosensitive drum 31 is the moving direction of the surface of the photosensitive drum 31. The peripheral speed of the developing sleeve 33 is twice the peripheral speed (process speed) of the photosensitive drum 31. A flywheel 41 made of an SECC steel plate is coaxially provided at the end of the photosensitive drum 31 where the gear 38 of the rotating shaft 31a is provided.

A viscous fluid-filled damper 42 is coaxially provided at one end of the rotating shaft 34 of the developing sleeve 33. The viscous-fluid-enclosed damper 42 is similar to the viscous-fluid-enclosed damper 12 of the first and second embodiments, and has
3, the inertial body 44 and the silica gel 45.

The two-component developing unit is provided with a developer supply roller 46. The developer supply roller 46 charges the toner by stirring the developer and supplies the toner to the developing sleeve 33. Of the developer attached to the surface of the developing sleeve 33, excess developer is scraped off to form a thin layer of the developer, and at the same time, the developer for frictionally charging the developer attached to the developer sleeve 33 is a developer layer. A regulating member 47 is provided, and the developer layer regulating member 47 and the casing 32 form a developer storage section.

The developer supplied to the developer sleeve 46 is friction-charged by the developer layer regulating member 47 to form a magnetic brush 48, which is conveyed to the developing area, which is opposed to the photosensitive drum 31, to be subjected to the developing process. Go in.

The screw 49 conveys the toner tank housed in a hopper (not shown) into the developing device. The screw 49 and the developer supply roller 46 are given a driving force by a gear train (not shown) from the developing sleeve 33.

The operation of the two-component developing type electrophotographic digital copying machine having the above-described structure will be described. In order to develop the electrostatic latent image formed on the surface of the photosensitive drum 31, the casing 3 is used.
The developer in the developer reservoir formed by the developer layer 2 and the developer layer regulating member 47 is supplied to the developing sleeve 33 and the developer layer regulating member 47.
, Ie, the developing sleeve 3
The magnetic brush 48, which is controlled to have an appropriate thickness, is conveyed to a space where the photosensitive drum 31 and the developing sleeve 33 face each other, passing through a space having a wedge-shaped cross section formed by the member 3 and the developer layer regulating member 47.

A bias voltage is applied to the developer layer regulating member 47 by a doctor bias power supply (not shown). Since the voltage can be controlled by an applied voltage control unit (not shown), the electric field between the developer layer regulating member 47 and the developing sleeve 33 is controlled by controlling the bias voltage.

Not only the developer electromagnetically attached to the surface of the developing sleeve 33 but also the developer located near the developing sleeve 33 is conveyed by rotating the developing sleeve in the direction of the arrow y in FIG. . Here, since the space formed between the developing sleeve 33 and the developer layer regulating member 47 is wedge-shaped, the pressure with which the developer is pressed against the developing sleeve 33 increases as the developer is transported toward the developer layer regulating member 44. As a result, the developer is sufficiently charged.

Further, the electric field between the developing sleeve 33 and the developer layer regulating member 47 can be controlled by the bias power supply of the developer layer regulating member 47 to slightly control the amount of the developer adhering to the surface of the developing sleeve 33. it can. Developing sleeve 33
An excessive portion of the developer adhering to the surface of the developing sleeve 33 is scraped off by the developer layer regulating member 47, and a uniform developer layer is formed on the surface of the developing sleeve 33. This uniform developer layer is formed by the rotation of the developing sleeve 33.
Then, the electrostatic latent image formed on the surface of the photosensitive drum 31 by an electrophotographic process is developed.

As described above, in this developing device, the developer is pressed against the developing sleeve 33 by the electric field generated between the developer layer regulating member 47 and the developing sleeve 33, and the developer layer regulating member 47 and the developing sleeve 33 are formed. And the magnitude of the magnetic field of the magnet roller 50 in the developing sleeve 33, the developer is sufficiently triboelectrically charged and reliably held on the surface of the developing sleeve 33.

The mechanism operations such as charging of the photosensitive drum 31 and formation of an electrostatic latent image, cleaning of transfer residual toner, transfer to recording paper, and fixing are exactly the same as those in the above-described one-component developing system, so that detailed description is omitted. I do.

In the case of the above-described configuration, even when the rotation is stable at the beginning, if the gears and the coupling wear over time and the backlash increases, the rotational speed of the developing sleeve 33 may vary. That is, image unevenness may occur due to fluctuations in the rotational speed of the magnetic brush 48 formed on the developing sleeve 33.

Accordingly, by providing the viscous fluid-filled damper 42 on the drive shaft 34 of the developing sleeve 33 in order to obtain good peripheral speed stability, fluctuations in rotational speed and vibration of the developing sleeve 33 can be suppressed. In addition, good image quality without image unevenness in the sub-scanning direction (transfer paper transport direction) was obtained.

For example, the developing sleeve driving torque is 3 kg.
In the case of cm, the rubbing resistance when facing the photoreceptor depends on the gap between the photoreceptor drum 31 and the developing sleeve 33 and the magnetic flux of the magnet roller 50 in the developing sleeve 33, but is about 5 kg · cm. However, when a viscous fluid-filled damper 42 containing an inertial body 44 having a moment of inertia of 516 g · cm ² and silica gel 45 is additionally fixed and used, jitter density unevenness on an image of about 100 Hz to 120 Hz is prevented. can do.

This effect is independent of the process speed and is 2
Similar results were obtained from 5 mm / s to 320 mm / s. Further, as shown in the first embodiment, the photosensitive drum 31
In particular, by providing the viscous fluid-filled damper 42 coaxially, an even greater effect is achieved against jitter and banding on the image.

[0079]

According to the first aspect of the present invention, there is provided an electrostatic latent image holding member, and a developer holding member supported by a developing unit for holding and transporting the developer. In an image forming apparatus for visualizing an electrostatic latent image formed on a peripheral surface with a developer of a developer carrier, a rotating shaft of at least one of the electrostatic latent image carrier and the developer carrier is provided. A viscous fluid-filled damper that coaxially encapsulates a viscous fluid is provided to reliably form high-quality images that prevent jitter and banding due to torque fluctuations of the electrostatic latent image carrier and developer carrier. In addition, jitter can be prevented by the viscous fluid-filled damper having a small weight, so that the drive motor of the electrostatic latent image holder and the developer carrier can be reduced in size.

According to a second aspect of the present invention, there is provided a viscous fluid-filled damper having an outer shell that is coaxial with the rotation axis and rotates together with the rotation axis, and an outer diameter smaller than the inner diameter of the outer cylinder. Since the rotary inertia body is rotatable coaxially and freely with respect to the outer shell cylinder, and the viscous fluid is sealed between the circumferential surfaces of the outer shell cylinder and the rotary inertia body, the weight is small. The inertial member of this type can suppress the rotation speed fluctuation of the rotating member (the electrostatic latent image holding member and the developer carrying member), and the viscous fluid-filled damper also has a small weight, so the time required for stopping the rotating member is reduced. Etc. can be shortened.

According to the third aspect of the present invention, since the outer cylinder is integrally fixed to at least one of the rotating shafts of the electrostatic latent image holding member and the developer holding member, the gears and the coupling are not required. As compared with the used one, it is possible to further prevent the rotation speed fluctuation caused by the backlash between the viscous fluid-filled damper and the rotating member.

[Brief description of the drawings]

FIG. 1 is a first embodiment of an electrophotographic digital copying machine of the present invention.
FIG.

2A is a longitudinal sectional view of the viscous fluid-filled damper of FIG. 1 as viewed from the side, and FIG. 2B is a longitudinal sectional view of the viscous fluid-filled damper of FIG. 1 as viewed from the front.

FIG. 3 is a partially cutaway perspective view of the viscous fluid-filled damper of FIG. 1;

FIG. 4 is a second embodiment of the electrophotographic digital copying machine of the present invention.
FIG.

FIG. 5 is a second embodiment of the electrophotographic digital copying machine of the present invention.
FIG.

FIG. 6 is a third embodiment of the electrophotographic digital copying machine of the present invention.
FIG.

FIG. 7 is a third embodiment of the electrophotographic digital copying machine of the present invention.
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Developing unit 3 Developing roller 11 Rotary shaft 12 Viscous fluid sealing damper 13 Outer case 14 Inertia 15 Silica gel

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Tatsumi 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Takashi Sakai 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Nobuhiko Nakano 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation

Claims (3)

[Claims] 1. An electrostatic latent image carrier comprising: an electrostatic latent image carrier; and a developer carrier supported by a developing unit for holding and transporting the developer. In an image forming apparatus for visualizing a latent image using a developer of a developer carrier, a viscous fluid is sealed coaxially with a rotation axis of at least one of the electrostatic latent image carrier and the developer carrier. An image forming apparatus provided with a viscous fluid-filled damper. 2. The viscous fluid-filled damper includes an outer shell cylinder that is coaxial with the rotation axis and rotates with the rotation axis, and has an outer diameter smaller than the inner diameter of the outer shell cylinder. 2. A rotary inertia body coaxially rotatable with respect to a cylinder and freely rotatable, and a viscous fluid is sealed and formed between circumferential surfaces of the outer shell cylinder and the rotary inertia body. Image forming device. 3. The image forming apparatus according to claim 2, wherein the outer cylinder is integrally fixed to at least one of the rotating shaft of the electrostatic latent image holding member and the developer holding member.